Bacterial Bacterial diagnosis diagnosis Principle of collection sample and sending To avoid contaminants Collect sample time Before using antibiotics Sample come from main infectious To take notice of conservation in tranport The sample mast be fresh LABORATORY DIAGNOSIS AND PROPHYLAXIS OF LABORATORY DIAGNOSIS AND PROPHYLAXIS OF BACTERIAL INFECTION BACTERIAL INFECTION , Treatment of Bacterial Treatment of Bacterial Infection Infection
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Bacterial diagnosis Principle of collection sample and sending To avoid contaminants Collect sample time Before using antibiotics Sample come from main.
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Bacterial diagnosisBacterial diagnosis
Principle of collection sample and sending
To avoid contaminants
Collect sample time
Before using antibiotics
Sample come from main infectious site
To take notice of conservation in tranport
The sample mast be fresh
LABORATORY DIAGNOSIS AND PROPHYLAXIS LABORATORY DIAGNOSIS AND PROPHYLAXIS OF BACTERIAL INFECTIONOF BACTERIAL INFECTION , Treatment of Treatment of Bacterial InfectionBacterial Infection
• SamplesSamples of body fluids (e.g. blood, urine, cerebrospinal of body fluids (e.g. blood, urine, cerebrospinal fluid) are inoculated on the plates and isolated colonies of fluid) are inoculated on the plates and isolated colonies of bacteria (which are visible to the naked eye) appear after bacteria (which are visible to the naked eye) appear after incubation for one - several days incubation for one - several days ..
• Each Each colonycolony consists of millions of bacterial cells. consists of millions of bacterial cells. Observation of these colonies for size, textureObservation of these colonies for size, texture 质地质地 , color, , color, and (if grown on blood agar) hemolysis reactions, is highly and (if grown on blood agar) hemolysis reactions, is highly important as a first step in bacterial identification. important as a first step in bacterial identification.
• Whether the organism requires oxygen for growth is Whether the organism requires oxygen for growth is another important differentiating characteristic.another important differentiating characteristic.
Step 2.Step 2.• Colonies are Gram stained and individual bacterial Colonies are Gram stained and individual bacterial
cells observed under the cells observed under the microscope.microscope.
DIFFERENTIATION OF BACTERIAGRAM STAINGRAM STAIN
Gram NegativeGram Positive
To rapid diagnosisTo rapid diagnosis• DDirect microscopicirect microscopic observation of certain clinical observation of certain clinical
samples for the presence of bacteria can be helpful samples for the presence of bacteria can be helpful (e.g. detection of (e.g. detection of M. tuberculosisM. tuberculosis in sputum). in sputum).
a cb
Approaches to rapid diagnosis Approaches to rapid diagnosis without prior culturewithout prior culture• Certain human pathogens (including the causative Certain human pathogens (including the causative
agents of tuberculosis, Lyme disease and syphilisagents of tuberculosis, Lyme disease and syphilis梅毒梅毒 ) either cannot be isolated in the laboratory or ) either cannot be isolated in the laboratory or grow extremely poorly. Successful isolation can be grow extremely poorly. Successful isolation can be slow and in some instances impossible. Direct slow and in some instances impossible. Direct detection of bacteria without culture is possible in detection of bacteria without culture is possible in some cases.some cases.
COLONIAL MORPHOLOGY
固体培养基:菌落固体培养基:菌落 colonycolony ,菌苔,菌苔
Blood Agar PlateBlood Agar Plate
Step 3Step 3
• The bacteria are speciated using these isolated The bacteria are speciated using these isolated colonies. This often requires an additional 24 hr of colonies. This often requires an additional 24 hr of growth. growth.
• IdentificationIdentification: biochemical reactions; immunological : biochemical reactions; immunological method (using known antisera); drug sensitivity test; method (using known antisera); drug sensitivity test; etc. etc.
A simple approach to rapid diagnosisA simple approach to rapid diagnosis-1-1
• antigen detection isantigen detection is used in many doctor‘s offices used in many doctor‘s offices for the group A streptococcus. The patient’s throat for the group A streptococcus. The patient’s throat is swabbed and streptococcal antigen extracted is swabbed and streptococcal antigen extracted directly from the swab (without prior bacteriological directly from the swab (without prior bacteriological culture). The bacterial antigen is detected by culture). The bacterial antigen is detected by aggregation (agglutination) of antibody coated aggregation (agglutination) of antibody coated latex beadslatex beads 乳胶微球乳胶微球 ..
SSimple approach to rapid diagnosisimple approach to rapid diagnosis-2-2
• Serologic identificationSerologic identification of an antibody response (in of an antibody response (in patient's serum) to the infecting agent can only be patient's serum) to the infecting agent can only be successful several weeks after an infection has successful several weeks after an infection has occurred.occurred.
• include agglutination,precipitation, complement include agglutination,precipitation, complement fixation test,neutralization, etc.fixation test,neutralization, etc.
AGGLUTINATION IMMUNOFLUORESCENCE
ANTIGENIC STRUCTURE
Widal testWidal test
Serological agglutinated test
PATHOGENICITY :animal test model
Such as Susceptibility of Experimental host to clinical Isolate
By ELASA tesaBy ELASA tesa to rapid diagnosis to rapid diagnosis
By molecular biologicalBy molecular biological skills to rapid skills to rapid diagnosisdiagnosis
• Bacterial DNA sequencesBacterial DNA sequences can be amplified directly can be amplified directly from human body fluids (the polymerase chain from human body fluids (the polymerase chain reaction, PCR). In this fashion large amounts of reaction, PCR). In this fashion large amounts of specific genes or portions of genes can be specific genes or portions of genes can be generated and readily detected. For example, great generated and readily detected. For example, great success has been achieved in rapid diagnosis of success has been achieved in rapid diagnosis of tuberculosis.tuberculosis.
MOLECULAR-GENETIC METHODS USING RNA AND DNA SEQUENCES AS SPECIFIC PROBES
DNA HOMOLOGY AND G/C RATIOS (GENOMICS- DNA SEQUENCING)
DNA RESTRICTION LENGTH POLYMORPHISMS (RFLP) AND POLYMERASE CHAIN REACTIONS (PCR)
PHAGE SUSCEPTABILITY AND PHAGE TYPING
Diagram of a representative bacteriophage
Phage typing is used primarily to differentiate groups withinStaphylococcus and Enterobacteriaceae